Inverted drum feeder for powdered detergent

ABSTRACT

In the conductivity controlled feeding of detergent and detergent solution to a large automatic dishwasher or similar machine, it is disclosed that the dissolution and feeding of a detergent mass is efficiently accomplished through the use of a solid stream of detergent solution rather than a spray or other diversion of ordinary water; the dry powdered detergent mass can be supported by a screen and a heavier perforated support plate; the support plate includes an opening large enough to permit the passage of the solid stream of liquid into the detergent mass to dissolve the detergent.

nited States Patent 1191 Burge et al. 1 1 Nov. 26, 1974 INVERTED DRUM FEEDER FOR 3,149,758 9/1964 Bush et al. 222/189 POWDERED DETERGENT 3,595,438 7/1971 Daley et a1 23/271 Inventors: Richard Lee Burge; Charles Peter Wilson, both of Glenview, 111.

Assignee: Calgon Corporation, Robinson Township, Pa.

Filed: July 28, 1972 Appl. No.: 276,063

References Cited UNITED STATES PATENTS Stine McDow Pike et al 23/270 X Andrews 23/271 Primary ExaminerStanley H. Tollberg Attorney, Agent, or Firm-Rudolph J. Anderson; Dr. H. E. Westlake; Martin L. Katz [57] ABSTRACT In the conductivity controlled feeding of detergent and detergent solution to a large automatic dishwasher or similar machine, it is disclosed that the dissolution and feeding of a detergent mass is efficiently accomplished through the use of a solid stream of detergent solution rather than a spray or other diversion of ordinary water; the dry powdered detergent mass can be supported by a screen and a heavier perforated support plate; the support plate includes an opening large enough to permit the passage of the solid stream of liquid into the detergent mass to dissolve the detergent.

6 Claims, 2 Drawing Figures BACKGROUND OF THE INVENTION The present invention is an improvement on inverted drum detergent feeders such as generally disclosed and discussed in Daley et al U.S. Pat. No. 3,595,438. Prior to the present invention, it was commonplace to dissolve detergent-with water and to feed the solution formed thereby to an automatic dishwasher or the like in proportion to or in response to a signal representing the conductivity of the detergent solution in the washing machine. Such systems have suffered in the past from a great variation in the concentration of detergent actually delivered to the dishwasher; particularly near the exhaustion of the container of detergent, the detergent solution tends to be extremely dilute in comparison with the strong solutions delivered near the beginning of the cycle. Moreover, the solution obtained through dissolving the detergent mass with water must be held in a container generally separate from the dissolving container; this results in a relatively stagnant condition which causes caking and precipitation of detergent ingredients, particularly when the solution not only remains stagnant but can cool significantly from its original temperature during the stagnation period.

The particular device described in Daley et al, U.S. Pat. No. 3,595,438, has been found to be imperfect in several respects. For example, it has been found that the use of a conical supporting screen such as suggested by Daley et al. frequently results in incomplete dissolution of the detergent mass, and particularly results in a solid caking or residual undissolved detergent filling the extremities of the bottom portion of the drum. Because of the conical shape of the screen, it is difficult for dissolving water to reach some areas around the periphery of the cone. Dissolution is doubly difficult because of the limited flushing action provided by the plain water sprayed into the drum intermittently, and only when the level in the bowl drops due to removal of a small quantity of detergent solution from the container.

It will be understood by those skilled in the art that the inverted drum detergent feeders of the type discussed herein are those which are normally employed in such applications as the feeding of detergent solution to large automatic dishwashers and other mechanical washers such as are used in institutions, restaurants, industrial plants, and so forth. It is very common for these detergent feeders to be controlled by a conductivity measuring device which is triggered when the concentration of detergent in the washer tank falls below a predetermined strength, thereby calling for additional detergent. By the use of various valves and tap water pressure sprays, etc., the detergent is dissolved and/or directed to the washing machine in response to a signal representing low conductivity in the washer tank. It has been a problem, however, to provide a continuous, instantly available and plentiful supply of detergent solution for the conductivity feed controller. Because of the aforementioned defect in the Daley et al. device, this device has a tendency to deliver extremely dilute detergent solution, and, of course, is economically undesirable in so far as it permits undissolved detergent to stay in the drum and form a hard, relatively insoluble cake regardless of the amount of water sprayed into the drum. The Daley device dissolves only a minimum amount of the required detergent with a minimum of agitation and flushing action.

The reader may be interested in Schneider et al. U.S. Pat. No. 3,507,624, which exemplifies the various disclosures in the prior art employing the velocity of a liquid jet as an aid in dissolving a chemical.

Stine U.S. Pat. No. 2,371,720 discloses the use of a cone to support the detergent mass, the cone being inverted with respect to the Daley et al disclosure.

Johnson in U.S. Pat. No. 2,802,724 discloses an example of a flat, perforated screen which, however, is not used to support the detergent mass, but which rests on top of the detergent mass.

The Daley et al. disclosure incorporates a discussion of a prior art device which employed a twelve jet manifold in combination with a flat screen, which screen was apparently used to support the detergent mass. The disclosure also discusses a device manufactured by W. R. Grace & Co. which employed a two-inch screen over an opening in the detergent, through which a single jet of water was inserted. Our device differs from this in a very material respect.

SUMMARY OF THE INVENTION The concept of using a two-inch screen through which a single jet of fresh water was inserted was found to be commercially unacceptable because of the large quantity of undissolved detergent which built up around the outer edges and elsewhere, particularly at the bottom of the detergent mass. The 2-inch opening was not sufficient for the passage of detergent solution out of the detergent mass while the jet of water was passing into it. Our invention provides that the entire surface of the detergent mass is supported by a screen including a heavy plate or other perforated device capable of supporting the screen and detergent mass. The screen of relatively fine openings covers the entire surface, while the supporting perforated plate or other heavier unit is left open at the point where the single jet of water or detergent solution is to enter the detergent mass.

We have found that a mechanical dishwashing detergent or similar detergent may be dissolved from a large packed solid mass in a container most easily and efficiently through the use of a single solid stream having a high velocity; the stream being comprised, except at the very outset, of a solution of the detergent to be dissolved.

We accomplish this through the use of a means for forming a single solitary high velocity jet stream, a screen or other easily penetrated device for retaining the solid mass preferably in an inverted position, a receptacle for the detergent solution, and a high velocity pump situated to receive the detergent solution from the receptacle and recirculate it into the detergent mass through the high velocity jet.

The configuration of our preferred embodiment will be described with respect to the drawings.

FIG. 1 is a side elevational view, partly cut away, of the entire feeder in operation.

FIG. 2 is a perspective and exploded view of the screen combination and a collar adapted to be fitted on top of a detergent drum.

In FIG. 1, a detergent mass 1 located in drum container 3 is shown pierced in the center by a vertical jet of water 5 which emanates from the top of nozzle 7. The jet passes through a disk-like supporting element 9 and a relatively fine screen 11. Elements 9 and 11 act as supports for the detergent mass 1; the bulk of the dry and semi-dry material is unable to pass through the screen because of its compaction, while at the same time the dissolved material may pass through in the form of a solution. The liquid which is sent from nozzle 7 into the detergent mass receives its force and velocity from pump 13, which in turn is fed through tube 15 by a simple drain in reservoir 16, which contains detergent solution 17. This detergent solution is accumulated by gravity from the container above it. It is maintained at a given level by a level controller comprising a float 23 and a nozzle controlled thereby 21. Also connected to the pump 13 is an outlet 19 which directs detergent so lution through optional valve 25 to the dishwasher. The detergent solution is impelled by pump 13 not only to the jet 7 but also to the dishwasher through outlet 19. This ultimately results in a lowering of the level of solution in reservoir 17, thereby lowering the float valve 23, which calls for the addition of more water directly into the reservoir. Thus, it will be seen that fresh water passes only into the reservoir and not directly into the detergent mass. The water in the reservoir is thereby more or less continually kept in motion, which tends to reduce the deposition of detergent compound and precipitates.

in FIG. 2, the three main parts of the collar and screen assembly are shown. They are the collar 31 in cluding locking lugs 33, screen 35 and supporting plate 37, equivalent to elements 11 and 9, respectively, in FIG. 1. Supporting plate 37 has an orifice 39, in this embodiment about three inches in diameter located centrally in the plate.

Thus, it will be seen that our invention includes a method of delivering detergent solution to a mechanical washer such as a dishwasher comprising (a) dissolving dry powdered detergent by inserting an initial single jet of water upwardly into the center of an inverted drum of dry powdered detergent through a flat retaining screen, (b) collecting the detergent solution formed thereby in a reservoir below said inverted drum, (c) recirculating said detergent solution by inserting it in the form of a single jet into the center of said inverted drum, and pumping said detergent solution from said reservoir to a dishwasher or mechanical washer in response to a conductivity signal to maintain a desired conductivity in the washing machine.

Our invention also contemplates an apparatus for retaining dry powdered detergent in an inverted drum for dissolution thereof comprising a circular, relatively finely perforated screen, a support therefor having extremities coterminous with said screen and defining an opening near its center, and a collar around both the screen and its support adapted to be locked to the top of a drum.

Our invention may be applied to several conductivity controlled machines at once, by utilizing several lines in parallel to conduit 19, each valve 25 being operated by its own conductivity controller. The conductivity controller should also actuate pump 13. Persons skilled in the art will recognize that only one pump is necessary and that more than one machine may be fed at once.

The powdered or granular detergent of any conventional size and/or formula will be compact enough and coherent enough to be retained by a screen of ordinary screen mesh size. The support plate can be chosen as to accommodate the weight of the detergent, which will of course depend on the size of the drum. The support should be able to support the screen through many uses. The support need not, except for sealing purposes, if required, extend to the extremities of the screen around its entire periphery. The collar and locking lugs are designed to clamp the screen and support onto the drum not only throughout the dissolving procedure but also throughout the inverting procedure.

We do not intend to be restricted to the specific embodiments of our invention herein described. It may be otherwise variously practiced within the following claims.

We claim:

1. Apparatus for dissolving detergent comprising a flat screen and a flat support plate therefor for retaining finely divided detergent in an inverted drum, said support being perforated and having a large opening near its center, and, in combination therewith, means for inverting said drum together with said flat screen and flat support plate therefor, reservoir means positioned below the inverted drum to collect and store detergent solution, and means for directing a single stream of detergent solution upwards through said central opening and into the detergent.

2. A detergent dissolver for delivering detergent solution to a mechanical washing machine under control of a conductivity sensing device comprising (a) flat screen means for retaining finely divided detergent in an inverted drum, said screen means including a flat support plate therefor defining a opening near its center, (b) a reservoir adapted to collect detergent solution draining from said drum, (c) means for directing a single stream of detergent solution from said reservoir upwards through the central opening of the screen support means into a detergent mass, (d) means for adding fresh water to said reservoir in response to liquid level therein, and (e) means for delivering detergent solution from said reservoir to a mechanical washing machine in response to a conductivity controller.

3. Detergent dissolver of claim 2 in which the means for directing detergent solution into a detergent mass and the means for delivering detergent solution to a washer have a common pump.

4. Detergent dissolver of claim 2 including means for delivering detergent solution to more than one washer.

5. Method of delivering detergent solution to a dishwasher comprising (a) dissolving dry powdered detergent by inserting an initial single jet of water upwardly into the center of an inverted drum of dry powdered detergent througha flat retaining screen, (b) collecting the detergent solution formed thereby in a reservoir below said inverted drum, (c) recirculating said detergent solution by inserting it in the form of a single jet into the center of said inverted drum, and pumping said detergent solution from said reservoir to a mechanical washing machine in response to a conductivity signal to maintain a desired conductivity in the washing machine.

6. Method of claim 5 in which the initial insertion of water into the detergent powder is performed with water initially filling said reservoir. 

1. Apparatus for dissolving detergent comprising a flat screen and a flat support plate therefor for retaining finely divided detergent in an inverted drum, said support being perforated and having a large opening near its center, and, in combination therewith, means for inverting said drum together with said flat screen and flat support plate therefor, reservoir means positioned below the inverted drum to collect and store detergent solution, and means for directing a single stream of detergent solution upwards through said central opening and into the detergent.
 2. A detergent dissolver for delivering detergent solution to a mechanical washing machine under control of a conductivity sensing device comprising (a) flat screen means for retaining finely divided detergent in an inverted drum, said screen means including a flat support plate therefor defining a opening near its center, (b) a reservoir adapted to collect detergent solution draining from said drum, (c) means for directing a single stream of detergent solution from said reservoir upwards through the central opening of the screen support means into a detergent mass, (d) means for adding fresh water to said reservoir in response to liquid level therein, and (e) means for delivering detergent solution from said reservoir to a mechanical washing machine in response to a conductivity controller.
 3. Detergent dissolver of claim 2 in which the means for directing detergent solution into a detergent mass and the means for delivering detergent solution to a washer have a common pump.
 4. Detergent dissolver of claim 2 including means for delivering detergent solution to more than one washer.
 5. Method of delivering detergent solution to a dishwasher comprising (a) dissolving dry powdered detergent by inserting an initial single jet of water upwardly into the center of an inverted drum of dry powdered detergent through a flat retaining screen, (b) collecting the detergent solution formed thereby in a reservoir below said inverted drum, (c) recirculating said detergent solution by inserting it in the form of a single jet into the center of said inverted drum, and pumping said detergent solution from said reservoir to a mechanical washing machine in response to a conductivity signal to maintain a desired conductivity in the washing machine.
 6. Method of claim 5 in which the initial insertion of water into the detergent powder is performed with water initially filling said reservoir. 